Calling line and private branch exchange line identifier



June 17, 1952 w. H. "r. HOLDEN CALLING LINE AND PRIVATE BRANCH EXCHANGE LINE IDENTIFIER 6 Sheets-Sheet l Filed April 24, 1948 INVENTOR uff/.7.' HOLDEN ATTORNEY June 17, 1952 w. H.'1. HOLDEN CALLING LINE AND PRIVATE BRANCH EXCHANGE LINE IDENTIFIER File'd April 24, 1948 6 Sheets-Sheet? ---Ihll IIIIII H /NvE/vroR f HOLDEN ATTORNEY June 17, 1952 w. H. 1'; HLDEN 2,600,502

ALLXNG LINE AND PRIVATE BRANCH EXCHANGE LINE :mamma Filed April 24. 1948, 6 Sheets-Sheet 5 FIG. 3

/NvE/vroR By. H HOLDEN ATTORNEY June' 17, 1952 w.fH, T. HOLDEN 2,600,502

` CALLING LINE AND PRIVATE BRANCH EXCHANGE LINE IDENTIFIER Filed April 24,A 194e e sheets-sheet 4 Arrow/Ey June 17, 1952 w. T. HOLDEN 2,600,502

CALLING LINE AND PRIVATE BRANCH EXCHANGE LINE IDENTIFIER' Filed April 24. i948 e sheets-sheet 5 l v l 2 v l v l? 7'0 ALARM c//m//r Arron/v5? June 17, 19.52l w. H. 'r. HOLDEN 2,600,502 l CALLING LINE AND PRIVATE BRANCH EXCHANGE LINE IDENTIFIER Filed April 24, 1948 6 Sheets-Sheet 6 FIG. 6

ATTORNEX Patented June 17, 1952 UNITED STATES PATENT. oFFlce-f@ CALLING LINE AND PRIVATE BRANCH EX- CHANGE LINE IDENTIFIER William H. T. Holden, Woodside, N. Y., assigner to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application April 24, 1948, Serial No. 23,043 A This invention relates to systems for identifying the stations of telephone and similar lines.

In Patent No. 2,484,612 dated October 1l, 1949, there is disclosed a system for identifying a telephone line by a single short impulse directed over a conductor associated with a calling line. The system disclosed in said application cornprises common bus-bars interconnected by, and connected, Asubscribers lines through gas-discharge diode tubes. The present invention is a modification of and an improvement on this system. I have discovered that distinct advantages may be obtained in reduced impedance at the bus-bars and practical elimination of surge eiects thereover by using rectifiers instead of gas-discharge'tubes, which is a feature of the present invention, and by other modifications. Furthermore, by arrangements herein disclosed, the present invention is adapted tothe identification of the individual stations of party lines as well as stations of individual lines, and to thev identification of private-branch-exchange stations.

Another feature of the invention is a means whereby the devices which register the identified designation are responsive to the rate of change of the magnitude of an impulse rather than merely to its magnitude alone. This makes possible the use of an extremely short impulse and results in a very rapid operation of the identifying system. Furthermore, the identifying equipment is not actuated by extraneous impulses lacking in the characteristic of a rapid rate of change of magnitude.

Still another feature of the invention is a means by which the identifying equipment is insensible to impulses of opposite polarity to those used for identication.

The above and other features of the invention will be more apparent from the accompanying description, the appended claims, and the drawings, which illustrate the invention as applied to the identication of the stations of individual, two-party, and private-branch-exchange lines, and in which:

Fig. 1 shows an individual line, a lprivatebranch-exchange line, and a portion of the equipment for identifying individual lines and ringparty stations of two-party lines;

Fig. 2 shows a two-party line and a portion of the equipment for identifying tip-party stations of two-party lines. In this figure, the pulse generator for the identifying equipment is indicated;

Figs. 3, 4, 5 and 6 show the remainder of the 18 Claims. (Cl. 179-18) 2. c equipment for identifying individual 4linesiand the ring-party stations of two-party lines;v and Fig. '7 shows how the above gures should be placed in relation to one another to completely disclose the invention.

In many dialtelephone systems, each set of connector terminals is assigned a particular directory number. The conductors of a subscribers individual line are cross-connected to terminals of a line nder or other line-extending device for outgoing service and to terminals of a connector for incoming service, the connector terminals being those to which the directory. number of the subscribers line is assigned. Such a line, with one station Si, is shown in Fig. 1 crossconnected to line finder LFI and to connector Cl. the directory-number being assumed to .be 1234. Where there are tWo stations on a line, the conductors of the line are cross-connected to linefnder terminals foroutgoing'service'and to two sets of connector terminals, one set of terminals being that to which the directory number of jone of the stations is assigned and the other set of terminals being that to which the directory number of the other station is assigned. "The sleeve terminals of the two sets oficonnector terlminals are connected together. 1 Such a line, Iwith two stations S2 and S3, is shown' in Fig. 2 crossconnected to line nder LFZ and to connectors C2 and C3, the directory number of station S2 (and the terminals of connector C2) being assumed to be 0000, and the directory number of station S3 (and the terminals of yconnector C3) being assumed to be 9999. In the case of private branch exchange lines, some 'of said lines are arranged for outgoing service only" and do not have directory numbers assigned to them. These lines are Vconnected to line-nder terminals but are not connected to connector terminals..V A line of this kind, with a station S4, kis shown in Fig. l cross-connected to line finder LF3.

In the present embodiment ofvmy invention, I provide at least one; identifier which I call the ring-party identifier. This'identier is capable of identifying and determining the directory numbers of calling stations of individual lines and the directory numbers of calling ring-- party stations of two-partyl lines.V It may also be employed, as hereinafter described, to identify the private branch exchange from which a call is made bya station in such exchange, which is arranged for outgoing service only, and to determine the listed number of said private branch exchange, or the directory number of some other associated line. Where two-party lines are served, I provide a separate and similar identifier for identifying tip-party stations. Where no two-party lines are involved, this identier may be omitted.

As in the system of my before-mentioned patent each identifier comprises one common busbar foreach possible combination of thousands and hundreds digits of directory numbers and one common bus-bar for each possible combination of tens and units digits of directory numbers. In Fig. 1, bus-bars RTHUO RTI-199 are the bus-bars of a ring-party identifier for combinations of thousands and hundreds digits of director numbers and bus-bars RTUilii RTUSS are the bus-bars of the same identifier for combinations of tens and units digits of directory numbers. In Fig. 2, bus-bars TTHQB 'I'.IHBS are the bus-bars of a tip-party identifier for combinations of thousands and hundreds digits of directory numbers and bus-bars 'IIUl TI'USSgare the bus-bars of. the same identifier for combinations of tensand units. digits of directory numbers; It will be observed that the bus-bars are `alike Vforthe two identiers.

In the present embodiment of the invention, identified directory numbers are indicated to registering or recording devices by energizing two oi -agroup of five conductors for each digit of directory number to be registered or recorded. The five conductors in each group are arbitrarily vdesignated (1), (2), (4), and (7), respectivel-y, and combinations of these conductors are energized to indicate the different digits as follows:

Conductors `-Ineach of Figs. 3 to 6, a set of iive conductors, designated as above, is shown, and a responsive recorder is indicated, which may be of any suitable type, such as, for example, the one shown in Patent No. 1,174,427 to C. L. and H. L. Krum, i

dated March '7, 1916, except that the recording magnets thereof are wired to the involved tubes (0)-(7) in said figures instead of to the contacts of a keyboard as shown in the patent. The recorders of Figs. 3 to 6 are for recording the thousands, hundreds, tens and units digits of directory numbers. respectively. They may, of course, be combined in one recorder. This arrangement for recording digits has the advantage of requiring less-complicated recording means than a system,

-such as the one shown in my above-mentioned copending application, in which one conductor is energized for each digit to be recorded. In carrying out the system of the present invention, I have provided one relay for each bus-bar, relay R99 being provided for bus-bar RTHSS, relay R12 for bus-bar RTHIZ, etc. The relays R99, R12, etc. control circuits comprising gas-discharge tubes shown in Figs. 3, 4, 5 and 6. The relays, tubes, land associated circuits shown are those for the ring-party identifier. Similar relays and circuits :are provided for the tip-party identifier, but since these are duplicates of those shown for the ringparty identifier, it is not thought necessary to 'show them in the drawings.

The relays R99, RIZ, etc. respond to pulses transmitted from the bus-bars, and, in turn, apply pulses to the tubes TH! TH5, Hi H5, TI T5, and UI U5, as described later. Other suitable means, such as electronic devices or rectiers, could be used in place of said relays, either to `produceandapply to said tubes pulses in accordance with those received from the bus-bars, or to transmit the pulses from the busbars directly to said tubes.

'I'he identiiers are actuated by a pulse generator PG, indicated but not fully disclosed in Fig. 2, which continuously produces positive pulses. This generator may be of any suitable type and reference may be had to my abovementioned patent for a disclosure of a suitable form ofsuch a pulse generator.

In the present invention, the identiers also comprise pairs of rectiiiers, such as rectifiers RCA and RCB. These may be of any suitable well-known type, vpreferably the geranium type. One pole of one rectiiier is connected to one of the bus-bars of one group and. one pole of the other rectier is connected to one of the bus-bars of the other group in one identifier. Forexample, one pole of rectifier RCA is connected to bus-bar RTI-112 of the ring-party identifier whichis assigned to the thousands and hundreds digit combination 12, While onepole of rectifier RCB is connected to bus-bar RTU34 of 'the ring-party identifier which is assignedzto the tens `and units digit combination 34. The `pair vof rectifiers RCA and RCB are, therefore, connected to the two groups of bus-bars .of the vring-party identier in accordance with .the number 1234. Similarly, one pole of irectier RCG is connected to bus-bar TTHSS of the'tip-partyidentier which is assigned to the thousands and hundredsdigit combination 99, whiley one pole of rectiiier RCH is connected to bus-bar TIUilof the tip-party identifier which is assigned tothe tensand units digit combination 99." The pair ofv 'rectiers RCG and RCH are, therefore, connected to the tip-party identier in accordance'with the number 9999. Other pairs of rectiflers are similarly connected in'accordance with other numbers so that there is one pair of rectifi'ers foreach directory number to be recorded.

The rectiers RCA, RCB, etc. are poledto .oppose high resistance to positive potentials at the bus-bars to which they are connected. The windings of reiays R93, RIZ, etc. are connected, through the winding of the polarized alarm relay P, to a battery BI of low voltage. It will be observed that the positive potential of battery BI is continuously applied through the Winding of relay P and the windings of relays R99, Rl2, etc. to the bus-bars and so to the rectifiers, and continuously maintains the resistance characteristics of the rectifiers, if said'rectiers are of the metallicoxide or similar type. The potential of battery BI- may have a Vvalue of 6-10 volts. The purpose of relay P is described later.

The sleeve terminal of each set of connector terminals which, as pointed out above, is associated with a particular directory number, is connected to the other poles of the pair of rectiiiers which represents the same directory number. Thus, the terminals shown of connector 'Cl are assigned the directory number 1234 and the sleeve terminal is connected to .rectifiers RCA and RCB which are connected to the bus-bars in accordance with said number. Similarly, the sleeve terminal 5i of connector C2 is connected to rectifiers RCC and RCD for the directory number 0000, while the sleeve terminal E2 of connector C8 is connected to rectifiers RCG and RCH for the directory number 9999. When a subscribers line is cross-connected to connector terminals for incoming service (which cross-connection is made in accordance with the directory number or numbers of the station or stations of said line) it is thereby automatically associated, throughrectifiers, with the appropriatebus-bars of an identier, or identiers.

In the case of a private-branch-exchange line arranged for outgoing service only, such as the P. B. X line shown in Fig. 1, there are, however, no associated connector terminals. In this case the sleeve terminal 53 of the line finder LFS is cross-connected to the appropriate poles of each of two additional rectifiers RCE and RCF, the other poles of which are cross-connected to busbars of an identier Vin accordance with the directory number it is desired to record when a call is made from said line. It is assumed that station S4 is a station of the private branch exchange which also includes station S I, and whose listed directory number is 1234. In order that said number will be recorded, as described later, on a call from station S4, rectifiers RCEl and RCF are cross-connected to bus-bars RTHIZ and RTI-T34, respectively.

When a call is made from station SI, the line of said station is extended in the usual manner by line finder LFI. Then, when it is desired to identify station SI and to record its directory number, a relay RI, which may be any suitable relay, preferably in the trunk to which the line of station SII is extended, is operated in any suitable manner. A short pulse of positive high voltage from pulse generator PG is thereby transmitted over conductor 54, contacts of relay RI, and conductor 55 to the anodes of all the gasdischarge triode tubes THI .TH5, HI H5, TI .-T5 and UI U5 of the ring-party identier. The starting element of each of these tubes is maintained at positive potential, as shown in the drawing. For example, the starting element of tube TI-IZ is maintained at positive potential by positive battery through resistors 5R and 4R. However, this potential is insuicient to cause said tube to conduct even when itsanode is also supplied with positive potential by thepulse described above. Any of said tubes will conduct when its anode is supplied with positive potential by the pulse described above only if, at the same time, its starting element is made more than normally positive. -Said pulse from pulse generator PG is also transmitted through sleeve contacts 56 of line finder LFI and the cross-connection between terminals 5'! and 50 to rectifiers RCA and RCB. Said rectiiers are poled to offer a low resistance to this pulse which, therefore, passes with little diminution through said rectiers. The'pulse through rectier RCA is transmitted to bus-bar RTHI2, thence over conductor 58 through the winding of relay RI2, conductor 6D, and the winding of polarized relay P tothe low-voltage source BI. Since it is desirable, in order to minimize the holding time of the identifying equipment, that the pulse from pulse generator PG be short, the peak voltage of the pulse should be suiliciently high to cause operation of relay RI2. Relay P, however, is polarized to respond only to current ow in the opposite direction and does not operate. Of course, if a negative pulse is applied by pulse generator PG or by any other means, it will be so attenuated by the rectifiers that relays RIZ and P will be unaffected thereby. When relay VRIZ operates. its No. 1 contacts apply positive battery to the junction of resistors IR and 2R thereby making the starting element of the tube RTH I (which :does not normally conduct) sufficiently positive so that, on a positive wave of alternating current from the source AC, said tube conducts over a circuit extending from said source through the anode-cathode space of said tube and resistor 3R to negative battery. The cathode of said tube, Which is normally negative, is thereby suddenly made positive, producing a positive p-ulse through rectifiers RCI and RC2 which are poled to offer a low resistance to said pulse. The positive pulse through rectier RCI produces a corresponding positive pulse from capacitor CI to the junction of resistors 4R and 5R. This raises the potential of the starting element of tube THZ and, at the same time, the anode of said tube is supplied with positive potential by the -pulse transmitted from pulse generator PG, as described above. Said tube, therefore, momentarily conducts and its cathode is thereby suddenly made positive by the voltage drop in resistor 5R, producing from capacitorC2 a positive pulse to the starting element of tube IT. This starting element is normally maintained positive by positive battery through resistor IR but insuiiciently so for said tube to conduct. The positive pulse from capacitor C2, however, raising the potential of the starting element, causes this tube to conduct over a circuit extending from positive battery through the anode-cathode space of said tube, a responsive element in the recorder RGI, and the winding of magnet MI to ground in said recorder. The responsive element in the recorder is thereby actuated to record the energization of the conductor having the designation (1) In a similar manner, the pulse through rectier RC2 actuates tubes THI and 2T to energize the conductor having the designation (0) and to actuate a responsive element in recorder RGI connected thereto. The combination (0) (1) `is thereby recorded which, in accordance with the code previously given, corresponds to the digit 1, which is thereby recorded. vThis is the thousands digit of the directory number 1234? of the calling station SI. Tubes IT and 2T continue to conduct and magnetl MI is thereby energized until the circuit ground in recorder RGI is removed by any suitable means. Said tubes thereupon cease to conduct and magnet MI is deenergized.A The deenergization of magnet MI actuates the usual mechanism for advancing the recording medium to receive the next recording operation.

The No. 2 contacts of relay RIZ apply positive potential over conductor 6I, actuating tube RHZ in the same manner as described above for tube RTHI. Tubes T3 and 3T are thereby actuated by a pulse through rectifier RC3 and tubes TI and 4T are actuated by a pulse through rectier RC, in the manner described above for tubes THZ, IT, THI, and 2T. Two conductors having the designations (0) and (2) and corresponding responsive elements in recorder RGZ are thereby energized to register or record the combination which correspondsto the digit 2, which is the hundreds digit of the directory number 1234 of station SI. Magnet M2 is also operated in the same manner as magnet MI.

The pulse through rectifier RCB to bus-bar RTU34 and over conductor 62 operates relay RR34 in the manner described above for relay RI 2. Positive potential is thereby applied to tube R'Is and, over conductor 6,3, to tube. R'Ul,` acmating* said tubes and in turn, tubes H3, 5T; H2, 6T, U4, TT', Ul' and Tare actuated', Combinations of conductors. and responsivev elements in the recorders RGS and RG# are thereby energized to record the digits 3 and 4, which arev the tens and units digits, respectively, of the directory number 12B/l of station Si. Itis not thought necessary to describe these latter operations in detail vas they are exactly similar to the operations already described andare readily followed from the descriptions already given. It may be noted, however, that the rectiers RCI, RC2, ctc. prevent the actuation of` tubes other than those named. above. The positive pulse through rectifier RC3, for example, which actuates tube T3, is unable to pass through the high resistance of rectifier RC5 to cause actuation of tube T5. It will be observed also that these rectiers. are normally supplied with potential, for example, negative potential through resistor 3Ry to rectifiers RC5 and RC2, which maintains their resistance characteristics.

In identifying station SI and recording its directory number, as described above, relay Rl need be operated only long enough to transmit one pulse from the pulse generator PG. However, it can do no harm to operate said relay for a period long enough to transmit more than one pulse. required, may serve to ensure the operation of relays Rl 2 and En. i should they fail to operate on the rst pulce. Said relays remain operated only for lshort periods since they are operated by short pulses, but they need remain operated only lonsvv enough to actua te tubes RTl-li, etc.

t will also be observed that tube Til? (ior example) is not actuated directly by the pulse from tube RTHl and tube iT is not actuated directly by the pulse from tube THQ. rlhe capacitor Cl prevents any steady potential from tube RTHG from reaching the starting element of tube 'Ti-I2" and the capacitor C2 prevents any steady potential from tube THE from reaching the starting element. of tube iT. riube THE, for example, is actuated by the rise of potential atits starting element and said potential rises suilciently to nre sai-d tube only if the potential at the cathode of tube HTH! rises rapidly compared to the time-constant of the circuit of capacitor Ci. ily suitable choice oi the elements of this circuit, said time-constant may be made sufliciently small so that tube THZ is not actuated byva compara-tively slow rise of potential through rectifier RCI, for example, a rise of sine-wave characteristic. Yet it is a characteristic of gasdischarge tubes, such as tube RTHI, that, when fired, the potential o1 the cathode rises rapidly and this rise is suiiciently rapid to induce -a corresponding rise at the starting element of tube THZ which is sufficient to fire the latter tube. But tube THE is actuated in response to the operation of relay Ri?. Said relay, therefore, need only beoperated long enough to fire tube RTI-Il, which time is, at the maximum, one cycle of the alternatingmurrent from the source AC. Relay R12 is, however, operated by the pulse supplied byv pulse generator PG over conductor 58 applied to the calling .line to identify said line. In the ,present invention, therefore, as in the disclosure of my copending application mentioned above, the pulse applied to a line to identify it may be very short. As has been pointed out abovahcwever, the tubes IT, 2T, etc. which control the recording. devices remain actuated until released The additional pulses, While not nor rally l to; ensure the satisfactory operation of; Said de:- vices. A

It will be apparent now without furtherdetailed description, that, when a call is made by station S4, the line of said station extendedby line under LFS, and` relay R2 operated to identify said station, a pulse is transmitted from pulse generator PG through contacts of said relay, sleeve contacts E4 of line lnder LFS, rectiiiers RCE and RCF, andthe cross-connections from said rectiners to bus-barsV RTI-1112 and RTU34. thereby actuating the equipment, in the manner described above, to record the directory num-ber 1234.

When; a call is made bystation S2, the line o saidstation is extended by line nder LFZ.4 and relay R3 operated to identify said station, a pulse from pulse generator-PG is transmitted through contacts of saidA relay, sleevel contacts 65 of line finder LFZ, the cross-connection betweenterminals 65 and 5l, andi conductor 61 throughllectiners RCC and RCD to bus-bars RTI-IDU and RTUEi oi thering-party identier. This pulse is also transmitted through the cross-connection between terminals 5l and` 52 and through rectiers RCG and RCI-I to bus-bars TTI-199 and TIU of the tip-party identier. The pulseis transmitted also through contacts of` relay R3, back contacts of relay PT and conductor 55 to the anodes of tubes of; the ring-party identier. Relay T is the well-known party-test relay, such as is shown, for example, and designated 122 in the patent to W. H. Scheer. No. 2,332,015, issued October 19, 19.43. When a tip-party station calls. the line is grounded at said station andrelay- PT operates to said ground While, on a calll from a ring-party station, there is no groundonthe line and relay PT does not operate. Sincestation S2 is a ring-,party station, relayPIf is notoperated in thepresent case. The pulse on bus-bars RTHUQ and RTUGG of the ring-party identifier, in conjunction with the pulse on conductor 55. actu,- ates the ring-party identifier, in theY manner a1- ready described, to record thev number 000(l," which is the directorynumberv of station S2. No pulse to the tip-party identifier corresponding to the pulse on conductor 55 is furnished and the pulse on bus-bars TTHSB-and TTU99 of thetipparty identifier-is, therefore, ineffective.

When, however, a call is made by station S3, the line isV extended byline iinder LFZ, and relay R3 is operated to identify said station, a pulse from pulse generatorPG is transmitted through contacts of relay R3 and sleevecontacts 65 of line,-nderLF2 to the four bus-bars namedabove. Station SS beingV a tip-party station, relay PT is now operated. Means are familiar in the art whereby stations on two-party lines may be automatically identiedin respect to Whether the tip station (as tip station S3, for example) or the ring station (as ring station S2, forexample) is calling. Patent No. 1,823,688, issued to H. Hovland on Septemberfl, 1931, illustrates an arrangement for identifying a particular calling station on a two-party line; relay 3| therein, corresponding to relay PT in the present disclosure, operating when the tip station is calling andremaining normal when the ring station is calling. The pulse from pulse generator PG is, therefore, also transmitted through contacts of relay R3, front contacts of relay PT, and conductor 68 to the tip-party identiiier (conductor 68 in thel tipparty identifier corresponding to conductor 55 of the ring party identier) No pulse is transmitted to conductor 55. The pulseon bus-bars TTI-199 and I"i`.l99,in conjunction with the pulse on conductor 68; is, therefore, eifectivelto actuate the tip-partyidentier, in the manner already described, to .record the number 9999, which is the directory number of station S3, while the pulse on bus-barsR'I-HllandRTUt of the ringparty identifier-is ineffective.

' Because .of the'highv reversesresistance of rectiflers,accumulatedf high potentialszdrain but slow- 'ly through-them.' Such potentials-on the bus-.bars

may drain through `the windings of the relay Rill! R99Mand the winding of relay P'tolbattery B-B'l'. Resistors,-such as resistor BR, areprovided'to permit abnormal charges on the capacitors,

suchas capacitor C I, to be dissipated. The batteryA i connected totheseresistors should have the same potentialas the battery connected toA the cathode. resistors-sumas resistor 3R, on the opposite side of itheirectiflers.

A grounded. bus-bar'. will, however, render ineffective all: pulses transmitted to it. In the present embodiment of my invention, if any bus-bar, for example, bus-bar RTU34, .becomes grounded, polarizedy relay P operates over a circuit extendingA from battery Bl through the winding of said relay, the winding of'relay RRSA, and conductor 62 to the ground on bus-bar RTU34. The contacts of relay E actuate ani7 suitable form of alarm circuit.

I have .illustratedmy invention in connection with a telephone system in which directory numbers yof :four digits arerecorded as identifications oi' calling stations. My. invention is, however, not limited-toI systems ofv this character. It may b-e applied, in conjunction. with the teachings of my above-mentioned copending application or independentlythereof, to 'other systems and for registering,- recording, 'or indicating directory numbers of moreor less than` four digits or identifications other than. directorynumbers. If registering only'of the identification is required, registering means may be substituted -for the recorders RGl RGB. Other applications, without departing from the spirit ofthe invention. will be apparent to those skilled inthe art.

What -is claimed is: c

i. ln combinatioma line having an identifying designation, a terminalindividu'alto sadiline, rectifying' devices 'connected .to said'. terminal, autematici-means' for applying an impulse to said 'rectifierv devices over. said. terminal, means for producingother' impulses, means vresponsive to said. impulsey throughv said. `rectifying devices for rendering', effective! said last-mentioned means, and meansy jointly responsivelto animpulse from said automatic means' and to said other impulses for' identifying 'said designation.

2. In combination, aline having-an identifying designation, a vterminal vindividual to said line, rectifying devices-connected tol said terminal, automatic means for' applyingan'impulse to said rectifying devices over said terminal, means for producingother limpulsesY of' variable magnitude,

means responsiveito said impulse throughA said rectifying devces..means" responsive; to the op- .eration OffSaid-lastmentmned-'meanSfO .Tendering said variable magnitude impulse producing meanseffective, .andymeans jointly responsive to said. impulse-.and to: thechan'ge in magnitude of an, impulse from Said variable impulse producing-means for identifying said designation.

3.- Incombination, aline having an identifying des.ienation.` arterminal. for; said line; means for .applyingarr impulse tosaid terminal,` nrstrectifvinel devices; .means-responsivefto. said, #impulseA through said iirst.rectityingtdevices; means@ v:rtl-v sponsive to said last-'mentionedmeanslvforfpto-.zf

dueing other impulses, seccndfrectifyifngedevices. and means responsive to: said otherqilmpulses through said second notifying-'devices oridn tifying saidV designation.

V4. In an identifying.- system; afl-ine havin sn identifying design-ation,Av atv-termin flforlsai ne. means for i applying-an impul's'efto said terminal, rst rectifyingdevices; means rsponsiv o id impulse through said first-viectifyingdevice for producing other -implses,seond vices through Whichsaid'the' I transmitted,v and means responsive tothe., in magnitude of .said transmitted impulses; identifying said designation.-

5. In an identifying system,- a=1ine haviiigan identifying designation composed ot "digits, a terminal individual-to saidrlinelz ctityingqdevices .connected tov said line terminal', "oondiictive paths indicative vof each ofsaidi digits, alitomatic means for applying' animpulse to'lsaid rectifying devices over said terminal, mean for directing said' impulse to each offsaidcondctive paths, means .for producing:otheiimpulses, means connected to each off' said-conductive paths responsive tofsaid impulsrthrou'g'l: "said rectifying. devices,- and' means -f jointly; resp nsive to said impulse'- and'to fan--inpulse frmL-s'ald means vfor producing: other.y impulses, 'eifctive over said last-#mentioned meansionrecordixg said digits.

e. In a systemfor Aidentit-ying@ailingstations, a line havingaplil-rality ofstations--thelfeon,

, each of said stations having. yan individual" 'terminal andV an identifying' .desig tion-.1 mean rsponsive,y to any. calling one jofv .said stations .for applying an impulse. to the terminator-sezionaliing' station', rectifyirigA devices, means responsive to said: impulse through. said.Y rectifying devices for transmitting` said impulsaad'nians responsive to thecliarigyii--magltudf-o "said transmitted impulse 'for identifying the f'desigrition o'f'sanicallirigstation 8. 'Ina system for identifying I calling stations, a line having a plurality .of 'stations-:thereon each or said-stations-naving an individual terminal and an@ identifying designatiom means rsponsiveV to any callingone of saidstationsfor 'applying'an impulse to the terminati ofV 'caliingV statior'i, meanscompris-in rectif responsive tofsalid :impulse-f l impulses, and` inea-ns' responsive to sa impresosvforiidentiiyigt callingstation l i e. In a system-for identifying-calling stations, a line'- having,` a5 plurality--of 'stations fthifeofifeioh of said stations having an individual terminal and .an videntifying designation, means responsive to any calling 'one ofsaid kstatiox'is 'for-applying an impulse to theyterminalof-'saidfcalling'statin, means comprising: rectifyingr-fdevices .responsive to saidfimpulse fonproduc-ing..others-impulses;' rid fineansiresponsive..l to: thefchan'gevini magntudelof said other` impulses for identifying the designationof said calling station.

10. In a system for identifying calling stations, a line having a plurality of stations thereon, each A of said stations having an individual terminal and an identifying designation composed of digits, conductive paths each indicative of a plurality of digits, means responsiveto any calling one of said stations for applying an impulse to the terminal of said calling station, means comprising rectifying devices responsive to said impulse to direct said .impulse to conductive paths indicative of the digits of the designation of said calling station, and means on each of said latter conductive paths responsive to said impulse for recording the digits of `the designation of said calling station.

11. In a system for identifying calling stations,

Y a line having a plurality of stations thereon. each of said stations having an individual terminal and an identifying designation composed of digits, conductive paths each indicative of a plurality of digits, means responsive to any calling one of said stations for applying an impulse to the terminal of said calling station, means comprising rectifying devices responsive to said im- Ypulse to direct said impulse to those of said conductive paths which are indicative of the digits of designation of said calling station, means on each of said latter conductive paths responsive to said impulse to produce other impulses, and means responsive to a change in magnitude of said other impulses for recording the digits of the designation of said calling station.

l2. In a signaling system, a rst line having an identifying designation, a second line, a terminal for said second line, rectifying devices, a first source of impulses and a second source of impulses, means for applying an impulse from said first source to said rectifying devices over said terminal when said second line is actuated, and means jointly responsive to the impulse applied to said rectifying devices and to an impulse from said second source for identifying the designation of said first line.

13. In an identifying system, a line having an"v identifying designation composed of digits, a terminal individual to said line, a first plurality of conductive paths indicative of digits, means 4for applying a iirst impulse to said terminal, f

means comprising rectifying devices for directing said rst impulse from said terminal over those of said conductive paths which are indicative of the digits designating said station,

means responsive to said first impulse for pro-V ducing other impulses, means including a second plurality of conductive paths indicative of digits, said other impulses being selectively transmitted over said second plurality of conductive paths in accordance with the digits designating said line, means for applying a second impulse to all the paths in said second plurality of conductive paths, and means in those conducvtions having a terminal individual thereto and an identifying designation, means for applying impulses to said terminals, two identifiers each responsive to said impulses over said terminals,

means responsive to one of said stations when actuated for actuating one of said identifiers for response to said impulses, thereby to identify the designation of said station, and means responsive to another of said stations when actuated for actuating another of said identifiers, thereby to identify the designation of said other station.

15. In an identifying system, a line having a plurality of stations thereon, each of said stations having a terminal individual thereto and an identifying designation, means for applying impulses to said termanls, two. station identifiers, means responsive to one of said stations when actuated for directing said impulses over both of said terminals to each of said identifiers, means responsive to said actuated station for applying other impulses to one of said identiers, means jointly responsive to said directed impulses and said other impulses for actuating said one identier to identify the designation of said actuated station, means responsive to the actuation of said other station for directing said other impulses to said other identifier, and means jointly responsive to said directed impulses and said other impulses for actuating said other identifier to identify the designation of said other actuated station.

16. In an identifying system, a line having an identifying designation composed of digits, a terminal for said line, a first plurality of conductive paths, means for applying a first impulse to certain of said paths over said terminal, means in said certain conductive paths responsive to said rst impulse, a second plurality of conductive paths for each of said digits, means for applying a second impulse through said responsive means to those conductive paths in said second plurality of conductive paths which are representative of the digits of said line, means for applying a third impulse to each path Y in said second plurality of conductive paths, and

means responsive jointly to said second impulse and to said third impulse on the paths to which said second impulse was applied for identifying the digits of said station.

17. In an identifying system, a line having an identifying designation composed of digits, a terminal individual to said line, conductive paths indicative of digits, rectifying devices connected to said terminal and to those of said conductive paths which represent the digits of said line, a rst source of impulses, means for applying an impulse from said source to said latter paths over said terminal and said rectifying devices, means connected to said latter paths responsive to said impulse, a second source of impulses, and means jointly vresponsive to the operation of said responsive means, to an impulse from said second source of impulses, and to an impulse from said first source of impulses for recording the digits designating said line.

18. In an identifying system, a line having an identifying designation composed of digits, a

. terminal individual to said line, conductive paths representative of digits, rectifying devices connected to said terminal and to those of said conductive paths which are representative of the digits of said line, a rst source of impulses and a second source of impulses, means for applying an impulse from said irst source over said terminal and through said rectifying devices to each of said latter conductive paths, means operative in response to said impulse over each -of said paths, and means jointly responsive to the operation of said last-mentioned means and to an impulse from said second source for identifying all of said digits.

WILLJAM H. T. HOLDEN.

REFERENCES CITED The following references are of record in the le of this patent:

Number 14 UNITED STATES PATENTS Name vDate Bascom Mar. 27, 1928 Horton June 10, 1941 Taylor Aug. 11, 1942 Taylor Oct. 20, 1942 Williams Mar. 30, 1943 Haigh Jan. 4, 1944 Dehn et al. Oct. 11, 1949 

